1. Field of the Invention
This invention relates broadly to a surface breathing vent for a breathing apparatus. More particularly, this invention relates to a vent device which is especially intended for air masks used in life support breathing systems, such as those used in scuba diving or toxic environments.
2. State of the Art
SCUBA equipment is used to permit a diver to breathe underwater from an auxiliary breathing gas supply. Typical SCUBA equipment generally includes a face mask, a mouth piece, a tank containing a breathing gas mixture containing oxygen, a hose extending from the tank, and a regulator coupled between the hose and the mouth piece which regulates the amount of breathing gas available to the diver and for permitting the release of exhaled breathing gas. A diver can remain underwater only for the duration permitted by the amount of the breathing gas in the tank. Conservation of the breathing gas is therefore paramount in determining the length of time available for a dive.
Referring to prior art FIG. 1, a xe2x80x98fullxe2x80x99 face mask 10 may be used in lieu of a separate face mask and mouthpiece. Such a mask is typical in military and commercial dive applications. The full face mask 10 includes a visor 12 which covers the eyes of the diver, and an oral-nasal cup 14 which surrounds the nose and mouth of the diver in lieu of a mouthpiece. The oral-nasal cup 14 is coupled to an external rigid support 16 to which a regulator 18 is attached. The support 16, especially in military and commercial dive applications, often includes a communications port (com port) 20 which leads directly into the oral-nasal cup 14. The com port 20 receives a microphone (not shown), thereby facilitating underwater communications between several divers and surface personnel. The mask 10 also includes a plurality of straps 22 which securely attach the mask to the diver""s head. Once correctly adjusted, the straps 22 help create a water tight fit for the visor 12 and oral-nasal cup 14 over the face of the diver. Thus, the mask is not readily attached to or removed from the diver""s head. Consequently, attachment of the mask 10 usually occurs prior to leaving shore, with the diver waiting in a dive boat with the full mask securely positioned over the diver""s face. Because it is not easy for the diver to remove the mask once it is attached, the diver is required to use the limited breathing gas in the tank from the time the mask is secured over the face. As such, valuable breathing gas is used prior to beginning the dive.
Referring now to prior art FIG. 2, in response to this concern, an after-market vent device 30, sold under the trademark GILL by Tech-One, Inc., may be installed in the mask 10. The vent device 30 permits ambient air to enter and exit the mask 10 with the mask attached to the diver""s head such that the diver may breathe ambient air, rather than breathing gas in the tank while waiting on the surface prior to a dive. The vent device 30 is installed by drilling a hole 32 into the side of the visor 12 at eye level. An inner collar 34 of the vent device 30 is then fit into the hole 32. Two O-rings 36, 38 between the visor 12 and the vent device 30 form a waterproof seal. An outer collar 40 is movable axially over the inner collar 34. Collar 40 can be pulled laterally outward from the mask to provide a vent opening 42 in the end of the device 30 which allows ambient air (dotted line 44) into and out of the face mask for breathing by the diver. Pushing the outer collar 40 inward over the inner collar 34 closes the vent opening 42 from ambient air and from water entry when under water.
However, the device has several drawbacks. First, the drilled hole 32 voids the manufacturer""s warranty of the face mask. Second, the pathway for ambient air to travel from the vent opening 42 requires the air to flow past the visor which tends to cause the visor to fog and obstruct the vision of the diver. In addition, the eye level position of the vent device 30 provides a rather large dead space between the mouth and nose of the diver and the vent opening 42 which permits CO2 buildup in the mask. Third, the vent device 30 projects outwardly from the side of the face mask 10 thereby creating the potential for entanglement with fish lines and the like. Moreover, there is the possibility that the vent device 30 may be caught or struck by an obstacle and cause the visor 12 to fracture or cause an imperceptible defect which during a dive allows water to enter the mask and flood the oral-nasal cup 14.
It is therefore an object of the invention to provide a surface breathing vent device for a full mask breathing apparatus which is specifically intended for use by scuba divers, firemen and others in toxic gaseous or oxygen-reduced environments.
It is another object of the invention to provide a surface breathing vent device which when installed in a full mask will not void the warranty of the mask.
It is a further object of the invention to provide a surface breathing vent device which will not disturb the integrity of the visor of the mask.
It is an additional object of the invention to provide a surface breathing vent device which will not protrude from the side of the mask.
It is also an object of the invention to provide a surface breathing vent device which is optimally positioned for breathing ambient air.
It is still another object of the invention to provide a surface breathing vent device which does not create dead space permitting the buildup of CO2.
It is still a further object of the invention to provide a surface breathing vent device which does not cause ambient air to pass in front of the visor, and therefore has a reduced likelihood of fogging.
In accord with these objects, which will be discussed in detail below, a surface vent device is provided for a full SCUBA mask which permits a diver wearing the mask to breathe ambient air prior to entering water. The vent device includes a support plate provided with an opening, the support plate being affixed to the rigid support of the face mask over the con port of the face mask, a bushing provided in the opening, and a vent barrel received in the bushing and movable between an open position in which ambient air can pass into the mask and a closed position in which water is prevented from entering the mask. The barrel includes a closed end and two lateral openings which permit air to pass therethrough when the barrel is in the open position. The barrel is provided with a first O-ring which prevents the inadvertent removal of the barrel from the support plate, a second O-ring which functions as a detent when the barrel is closed and further functions as a friction ring to maintain the barrel in an open position when so desired, and a third O-ring provides a water and air tight seal when the barrel is in a closed position.
A microphone may be attached to the vent device such that the vent device serves the dual purpose of a com port and a surface breathing vent. In addition, because of the location of the vent device over the com port, the air flow through the vent device travels directly into the mouth and nose and does not pass the visor of the face mask outside the oral-nasal cup. As a result, there exists relatively little dead space for the build-up of CO2and there is little chance that the visor will fog. Moreover, there is no need to drill or cut a hole in the visor; as such, the warranty of the mask is not affected. Furthermore, as two lateral holes are provided for the passage of air, a relatively larger vent area is provided than with the prior art device.
Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.